Assisted takeoff

ABSTRACT

A method of assisted takeoff of a movable object includes increasing output to an actuator that drives a propulsion unit of the movable object under a first feedback control scheme, determining whether the movable object has met a takeoff threshold, and controlling the output to the actuator using a second feedback control scheme different from the first feedback control scheme in response to the movable object having met the takeoff threshold.

CROSS-REFERENCE

This application is a continuation application of U.S. application Ser.No. 14/811,448, filed on Jul. 28, 2015, which is a continuationapplication of U.S. application Ser. No. 14/257,955, filed on Apr. 21,2014, now U.S. Pat. No. 9,126,693, which is a continuation applicationof International Application No. PCT/CN2014/074232, filed on Mar. 27,2014, the entire contents of all of which are hereby incorporated byreference.

BACKGROUND OF THE DISCLOSURE

Aerial vehicles such as unmanned aerial vehicles can be used forperforming surveillance, reconnaissance, and exploration tasks formilitary and civilian applications. Such vehicles may carry a payloadconfigured to perform a specific function. These aerial vehicles maytake off and land on a surface.

However, when traditionally controlled aerial vehicles take off from asurface, the feedback control systems used combined with the forceprovided by the surface can cause initial instability. Particularly,when a surface is sloped, the takeoff may not be vertical, and there maybe a greater probability of crashing or falling over. The takeoff oftenpresents a challenge for users, particularly inexperienced users, and ifthe aircraft is uncontrolled or unstable during takeoff, users willbecome nervous and cause the aircraft to crash.

SUMMARY OF THE DISCLOSURE

In some instances, it may be desirable to use takeoff methods which maypermit an aerial vehicle takeoff to be substantially smooth andvertical. Thus, a need exists for improved takeoff methods. The presentdisclosure provides systems, methods, and devices related to takeoffcontrols for the aerial vehicle. Existingproportional-integral-derivative (PID) controllers, due to memoryeffects of integration, will result in a ground force, which may causethe integration expression to be wrong and cause instability. Thedisclosure permits the elimination of integration during takeoff, untilthe aerial vehicle is determined to have left the ground. Controlsystems and methods described herein may directly output analog takeoffcontrol values, and after successful takeoff, seamlessly switch to a PIDcontrol. The determination may be made when to switch to a PID controlscheme based on an output to one or more motors of the aerial vehicleand/or an acceleration of the aerial vehicle.

An aspect of the disclosure is directed to a method of assisted takeoffof a movable object, said method comprising: increasing output to anactuator of the movable object under a first control scheme, wherein theoutput to the actuator results in the increase of an altitude of themovable object; determining, with aid of a processor, whether themovable object has met a takeoff threshold based on the output to theactuator, the output measured from an actuator, or velocity oracceleration of the movable object; and controlling the output to theactuator using a second control scheme when the movable object has metthe takeoff threshold.

In some embodiments, the movable object may be an aircraft capable ofvertically taking off and/or landing. The movable object may be anunmanned aerial vehicle. The unmanned aerial vehicle may be arotorcraft. The actuator may be a motor driving a propulsion unit of themovable object. The propulsion unit may be a rotor configured to providelift to the movable object.

The first control scheme may be a first integral control scheme. Anintegral value under the first integral control scheme may be set to adefault value. In some implementations, the default value may be zero.

The output may be increased by a constant value. Increasing the outputto the actuator may result in increasing overall propulsion of themovable object. The command may be provided by a remote terminal. Priorto receiving the command to increase the altitude of the movable object,a command may be received to start the actuator and placing the actuatorin an idle mode. The method may also include reducing the output to theactuator until the actuator is in an idle mode when the command toincrease the altitude does not exceed a predetermined value.

Optionally, the second control scheme may be a second integral controlscheme. Controlling the output to the actuator using the second integralcontrol scheme may include integral control of the vertical direction.Controlling the output to the actuator using the second integral controlscheme may include integral control over one or more of the following:front direction, rear direction, right direction, left direction, orattitude. In some cases, controlling the output to the actuator usingthe second integral control scheme may include using aproportional-integral-derivative control scheme.

Determining whether the movable object has met the takeoff threshold maybe based on the degree of output to the actuator. Determining whetherthe movable object has met the takeoff threshold based on the degree ofthe output to the actuator may include determining that the movableobject has met the takeoff threshold when the degree of the output tothe actuator exceeds a predetermined output value. Determining whetherthe movable object has met the takeoff threshold may also be based on ameasured velocity or acceleration of the movable object, measuredaltitude, or output measured from the actuator. Optionally, determiningwhether the movable object has met the takeoff threshold does not dependon signals received from a source external to the movable object.

In some instances, the takeoff threshold is met when (1) the output tothe actuator is greater than a first predetermined output value andacceleration of the movable object in a vertical direction exceeds apredetermined acceleration value, or (2) the output the actuator isgreater than a second predetermined output value. The secondpredetermined output value may be different from the first predeterminedoutput value. The second predetermined output value may be greater thanthe first predetermined output value.

Another aspect of the disclosure may be directed to a system forassisted takeoff of a movable object, said system comprising: a receiverconfigured to receive a command to increase an altitude of the movableobject; an actuator of the movable object, wherein the output to theactuator results in the increase of the altitude of the movable object;and a processor configured to determine whether the movable object hasmet a takeoff threshold based on the output to the actuator, outputmeasured from the actuator, or velocity or acceleration of the movableobject, and generate a signal used to control the output to the actuator(1) using a first control scheme when the movable object has not met thetakeoff threshold, and (2) using a second control scheme when themovable object has met the takeoff threshold.

The processor may be on-board the movable object. Alternatively, theprocessor may be provided on an external device separate from themovable object.

In some embodiments, the movable object may be an aircraft capable ofvertically taking off and/or landing. The movable object may be anunmanned aerial vehicle. The unmanned aerial vehicle may be arotorcraft. The actuator may be a motor driving a propulsion unit of themovable object. The propulsion unit may be a rotor configured to providelift to the movable object.

The first control scheme may be a first integral control scheme. Anintegral value under the first integral control scheme may be set to adefault value. In some implementations, the default value may be zero.

The output may be increased by a constant value. Increasing the outputto the actuator may result in increasing overall propulsion of themovable object. The command may be provided by a remote terminal. Thereceiver may be configured to receive a command to start the actuatorand place the actuator in an idle mode, prior to receiving the commandto increase the altitude of the movable object. The output to theactuator may be reduced until the actuator is in an idle mode when thecommand to increase the altitude does not exceed a predetermined value.

The second control scheme may be a second integral control scheme. Thesecond integral control scheme may include integral control of thevertical direction. The second integral control scheme may includeintegral control over one or more of the following: front direction,rear direction, right direction, left direction, or attitude. The secondintegral control scheme may include a proportional-integral-derivativecontrol scheme.

The processor may determine that the movable object has met the takeoffthreshold when the degree of the output to the actuator exceeds apredetermined output value. In some implementations, the processordetermines whether the movable object has met the takeoff thresholdbased on a measured velocity or acceleration, measured altitude, ormeasured output from the actuator of the movable object. The processormay determine whether the movable object has met the takeoff thresholdwithout relying on signals received from a source external to themovable object.

In some embodiments, the takeoff threshold is met when (1) the output tothe actuator is greater than a first predetermined output value andacceleration of the movable object in a vertical direction exceeds apredetermined acceleration value, or (2) the output the actuator isgreater than a second predetermined output value. The secondpredetermined output value may be different from the first predeterminedoutput value. The second predetermined output value may be greater thanthe first predetermined output value.

A method of assisted takeoff of a movable object may be provided inaccordance with another aspect of the disclosure. The method maycomprise: increasing output to an actuator of the movable object under afirst control scheme; determining, with aid of a processor, whether (1)the output to the actuator is greater than a first predetermined outputvalue and when acceleration of the movable object in a verticaldirection exceeds a predetermined acceleration value, or (2) the outputto the actuator is greater than a second predetermined output value; andcontrolling the output to the actuator by using a second control schemedifferent from the first control scheme when (1) the output to theactuator is greater than a first predetermined output value and whenacceleration of the movable object in a vertical direction exceeds apredetermined acceleration value, or (2) the output to the actuator isgreater than a second predetermined output value.

In some embodiments, the movable object may be an aircraft capable ofvertically taking off and/or landing. The movable object may be anunmanned aerial vehicle. The unmanned aerial vehicle may be arotorcraft. The actuator may be a motor driving a propulsion unit of themovable object. The propulsion unit may be a rotor configured to providelift to the movable object.

The output may be increased by a constant value. Increasing the outputto the actuator may result in increasing overall propulsion of themovable object. The method may also include receiving a command toincrease an altitude of the movable object. The command may be providedby a remote terminal. Prior to receiving the command to increase analtitude of the movable object, a command may be received to start theactuator and placing the actuator in an idle mode. The method mayinclude reducing the output to the actuator until the actuator is in anidle mode when the command to increase the altitude does not exceed apredetermined value.

The first control scheme may use an integral value that is set to adefault value. The default value may be zero. The second control schememay use integral control of the vertical direction. Controlling theoutput to the actuator using integral control may includes integralcontrol over one or more of the following: front direction, reardirection, right direction, left direction, or attitude. Controlling theoutput to the actuator by using the second control scheme may includeusing a proportional-integral-derivative control scheme.

The second predetermined output value may be different from the firstpredetermined output value. Optionally, the second predetermined outputvalue is greater than the first predetermined output value.

Furthermore, an aspect of the disclosure may include a system forassisted takeoff of a movable object, said system comprising: anactuator of the movable object; and a processor configured to determinewhen one or more of the following conditions are met: (1) an output tothe actuator is greater than a first predetermined output value and whenacceleration of the movable object in a vertical direction exceeds apredetermined acceleration value, or (2) the output to the actuator isgreater than a second predetermined output value, and generate a signalused to control the output to the actuator (a) by using a first controlscheme when neither of the conditions (1) or (2) met, and (b) by using asecond control scheme when at least one of the conditions (1) or (2) aremet.

The processor may be on-board the movable object. Alternatively, theprocessor may be provided on an external device separate from themovable object.

Optionally, the movable object may be an aircraft capable of verticallytaking off and/or landing. The movable object may be an unmanned aerialvehicle. The unmanned aerial vehicle may be a rotorcraft. The actuatormay be a motor driving a propulsion unit of the movable object. Thepropulsion unit may be a rotor configured to provide lift to the movableobject.

The output may be increased by a constant value. Increasing the outputto the actuator may result in increasing overall propulsion of themovable object. A receiver may be provided that is configured to receivea command to increase an altitude of the movable object. The command maybe provided by a remote terminal. The receiver may be configured toreceive a command to start the actuator and placing the actuator in anidle mode, prior to receiving the command to increase an altitude of themovable object. The output to the actuator may be reduced until theactuator is in an idle mode when the command to increase the altitudedoes not exceed a predetermined value.

In some embodiments, the first control scheme may use an integral valuethat is set to a default value. The default value may be zero. Thesecond control scheme may use integral control of the verticaldirection. Controlling the output to the actuator using integral controlmay includes integral control over one or more of the following: frontdirection, rear direction, right direction, left direction, or attitude.Controlling the output to the actuator by using the second controlscheme may include using a proportional-integral-derivative controlscheme.

The second predetermined output value may be different from the firstpredetermined output value. Optionally, the second predetermined outputvalue is greater than the first predetermined output value.

It shall be understood that different aspects of the disclosure can beappreciated individually, collectively, or in combination with eachother. Various aspects of the disclosure described herein may be appliedto any of the particular applications set forth below or for any othertypes of movable objects. Any description herein of aerial vehicles,such as unmanned aerial vehicles, may apply to and be used for anymovable object, such as any vehicle. Additionally, the systems, devices,and methods disclosed herein in the context of aerial motion (e.g.,flight) may also be applied in the context of other types of motion,such as movement on the ground or on water, underwater motion, or motionin space.

Other objects and features of the present disclosure will becomeapparent by a review of the specification, claims, and appended figures.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present disclosure will be obtained by reference tothe following detailed description that sets forth illustrativeembodiments, in which the principles of the disclosure are utilized, andthe accompanying drawings of which:

FIG. 1 illustrates an aerial vehicle taking off, in accordance with anembodiment of the disclosure.

FIG. 2 illustrates an example of a method for controlling takeoff of anaerial vehicle, in accordance with an embodiment of the disclosure.

FIG. 3 provides a high level schematic of an aerial vehicle, inaccordance with an embodiment of the disclosure.

FIG. 4 illustrates an unmanned aerial vehicle, in accordance with anembodiment of the disclosure.

FIG. 5 illustrates a movable object including a carrier and a payload,in accordance with an embodiment of the disclosure.

FIG. 6 is a schematic illustration by way of block diagram of a systemfor controlling a movable object, in accordance with an embodiment ofthe disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The systems, devices, and methods of the present disclosure provideassisted takeoff for an aerial vehicle from a surface, which enablesimproved control for a user. The aerial vehicle may be an unmannedaerial vehicle (UAV), or any other type of movable object. Oftentimes, afeedback control is used during flight of an aerial vehicle. Duringnormal flight operations, a proportional-integral-derivative (PID)flight control system is often used. However, during takeoff, memoryeffects of integration combined with ground forces may cause the meaningof the integration expression to go wrong. This can cause instabilityduring takeoff and may require complex maneuvers that many novice usersmay not be familiar or comfortable with. This can lead to crashing ofthe UAV during takeoff.

An assisted takeoff system, method, and device may be provided which mayreduce this instability during takeoff and permit novice users to easilycontrol the aerial vehicle during takeoff. While the aerial vehicle istaking off, the integral calculation may be removed from the feedbackcontrol. This permits direct output of analog takeoff control values.After it has been determined that the aerial vehicle has successfullytaken off (i.e., the aircraft is in mid-air), the feedback controlscheme may be switched to normal flight mode, which may include integralcontrol (e.g., PID control).

The switch from one feedback control scheme to another may be made whenit is determined that a takeoff threshold has been met. This may bedetermined based on information that is provided from on-board theaerial vehicle. For instance, the takeoff threshold may be deemed to bemet based on information regarding output to a motor of the aerialvehicle, and/or acceleration of the aerial vehicle. For instance, thetakeoff threshold may be met when at least one of the followingconditions is met: (1) output to the motor exceeds a first thresholdoutput value and vertical acceleration of the aerial vehicle exceeds athreshold acceleration value, or (2) output to the motor exceeds asecond threshold output value. Thus, the switch in the flight controlscheme may be made from a takeoff control scheme to a normal flightcontrol scheme when the takeoff threshold is met, indicative of when theaircraft has fully taken off from the surface, and it is safe to switchto the normal flight control. In some instances, the switch may be madewithout requiring any signals from outside the aerial vehicle. Theaerial vehicle may be self-contained in making the determination of whento make the switch in control schemes.

FIG. 1 illustrates an aerial vehicle 100 taking off, in accordance withan embodiment of the disclosure. The aerial vehicle 100 a may initiallybe resting on a surface 130 prior to takeoff. The aerial vehicle mayinclude one or more propulsion units 110 a. The propulsion units mayprovide lift to the aerial vehicle. When the aerial vehicle receives acommand to take off, it may lift off of the surface under a firstcontrol scheme. When the aerial vehicle 100 b meets a threshold 120indicative of whether the aerial vehicle has sufficiently taken off, theaerial vehicle may switch over to a second control scheme. Thepropulsion units 110 b of the aerial vehicle may then be controlled onthe second control scheme, which may be different from the first controlscheme.

In some embodiments, the aerial vehicle 100 a, 100 b may be a UAV, orany other type of movable object. The aerial vehicle may be arotorcraft. The aerial vehicle may have propulsion units 110 a, 110 bthat may be capable of causing the aerial vehicle to move. Thepropulsion units may provide lift to the aerial vehicle and permit theaerial vehicle to change altitude. The propulsion units may also causethe aerial vehicle to move laterally and/or change orientation. Theposition of the aerial vehicle may be controlled (e.g., altered ormaintained) by the propulsion units. The propulsion units may controlthe aerial vehicle with respect to one or more degrees of freedom (e.g.,e.g., 1-3 degrees of spatial disposition, 1-3 degrees of orientation).

The propulsion units 110 a, 110 b may be rotors that may be rotated toprovide lift to the aerial vehicle. The rotors may include one or morerotor blades that may spin about an axis. In some instances, a singlepropulsion unit may be provided on an aerial vehicle. Alternatively,multiple propulsion units may be provided for an aerial vehicle. Forexample, one, two, three, four, five, six, seven, eight, nine, ten ormore propulsion units may be provided on an aerial vehicle. Thepropulsion units may be driven by one or more actuators. The actuatorsmay be motors, such as AC or DC motors. The actuators may respond to acommand signal from a flight controller. The command signal may includeoutput to the actuators. In some embodiments, each propulsion unit maybe driven by a single actuator. Optionally, an actuator may drivemultiple propulsion units, or a single propulsion unit may be driven bymultiple actuators.

Initially, prior to taking off, the aerial vehicle 100 a may besupported by a surface 130. The surface may be a ground, structure,street, turf, water, movable object, living being, or any type ofsupport. In some instances the surface may be static. For example, thesurface may not be moving to a reference frame, such as the environment.In some implementations, the surface may be moving or movable relativeto a reference frame, such as the environment. The surface may or maynot change altitude or orientation.

In some embodiments, the surface 130 may be substantially flat. When theaerial vehicle is resting on the surface, a takeoff axis may besubstantially parallel to the direction of gravity g. In otherembodiments, the surface may be sloped. For example, when the vehicle isresting on the surface, a takeoff axis may be at an angle relative tothe direction of gravity. For example, the angle may be greater than orequal to about 5 degrees, 10 degrees, 15 degrees, 30 degrees, 45 degreesor 60 degrees. In some instances, the angle may be less than or equal toabout 5 degrees, 10 degrees, 15 degrees, 30 degrees, 45 degrees or 60degrees.

The aerial vehicle 100 a may receive a command to take off, and a flightcontroller may control the flight under a first control scheme before atakeoff threshold 120 is met, and may control the flight under a secondcontrol scheme after the takeoff threshold is met. The takeoff thresholdmay be indicative of when the aerial vehicle has fully taken off so thatthe vehicle can utilize a proportional integral derivative (PID) flightwithout the detrimental effects described elsewhere herein. Prior to thetakeoff threshold being met, the aerial vehicle may be in a takeoffphase. After the takeoff threshold has been met, the aerial vehicle maybe in a flight phase. Thus a two-stage process may be provided when theaerial vehicle takes off. The takeoff phase may use the first controlscheme. The flight phase may use the second control scheme.

In some instances, the first control scheme may be a control schemewhere an integral value is set to a default value. For example, thedefault value may be zero, or another default value. In some alternativeimplementations, the first control scheme does not use integral control.The second control scheme may be a control scheme that does use integralcontrol. In one example, the first control scheme may useproportional-derivative (PD) control, orproportional-integral-derivative (PID) control where the integral valuemay be set to a default value, such as zero. The second control schememay use proportional-integral-derivative (PID) control. In someembodiments, the first control scheme may have a PID setup where theintegral output is always zero. The second control scheme may permit theintegral output to be turned on. This may be applicable for bothaltitude and attitude control. For example, during a takeoff phase, boththe altitude and attitude control may have an integral value set to adefault value, such as zero. Alternatively, only one of the altitude orattitude control may have an integral value set to a default value, suchas zero. During a flight phase, both the altitude and attitude controlmay use normal integral control.

The first control scheme may have an integral control scheme where theintegral value is set to zero, or other default value, in the verticaldirection of the aircraft. The first control scheme may optionally havean integral value set to zero, or other default value, in the lateraldirections of the aircraft. The second control scheme may use integralcontrol in the vertical direction of the aircraft. The second controlscheme may use integral control in the lateral directions of theaircraft. Optionally, the first control scheme may result in the use ofPD control for both vertical and lateral directions of the aircraft. Thefirst control scheme may use PD control or PID control for attitudecontrol of the aircraft. Optionally, the second control scheme mayresult in the use of PID control for both the vertical and lateraldirections of the aircraft. The second control scheme may use PIDcontrol for attitude control of the aircraft. In some instances, aflight control scheme may have an integral control that isI_(out)=K_(i)∫₀ ^(i)∈(τ)dτ. In one example, the first integral controlscheme may keep I_(out) as a default value (e.g., constant numericalvalue). In some examples, I_(out) may be kept at zero. In someinstances, I_(out) may be kept as the same value. In some instances,I_(out) may vary by a small amount. In some instances, I_(out) may varyin a predetermined manner. Optionally K_(i) may be set to zero. In someinstances, the first integral control scheme may be implemented whilethe aircraft is in a take-off phase. A second integral control schemedifferent from the first integral control scheme may be implementedwhile the aircraft is in a flight phase. Normal integral control may beused.

In some embodiments, the control scheme that dictates flight may bedetermined by a flight controller of an aerial vehicle 100 a, 100 b. Theflight controller may output one or more command signals in response tothe control scheme being used. The command signals may be provided toone or more actuators that drive the propulsion units of the aerialvehicle.

The flight controller may determine which control scheme to usedepending on whether a takeoff threshold 120 has been reached. Theflight controller may make the determination whether the takeoffthreshold has been reached based on one or more sensed condition or datafrom one or more sensors. In some instances, a separate processor(on-board or off-board the aerial vehicle) may be used to determinewhether the takeoff threshold has been met. The separate processor mayprovide a signal to the flight controller indicative of whether thetakeoff threshold has been met. In some instances, once the flightcontroller has determined which control scheme to use, it may calculateoutput to the motors under the selected control scheme.

Two different flight control schemes may be used, depending on the phaseof a two-stage takeoff process. In various alternative implementations,any number of flight control schemes may be provided for a takeoffprocess that may have any number of stages. For example, three flightcontrol schemes, four flight control schemes, five flight controlschemes, six flight control schemes or more control schemes may be usedfor multi-stage take off processes having three, four, five, six or morephases. Any description herein of a two-control scheme system may applyto any type of multi-control scheme system. Multi-control scheme systemsmay have different threshold points indicating different points in thetakeoff process. The methods described herein to determine when atakeoff threshold has been met may be applied to any number of thresholdpoints.

FIG. 1 shows how after a takeoff threshold 120 has been met, the aerialvehicle 100 b may be clear of the surface 130 and may be ready to switchto a standard flight mode (e.g., PID control). In some instances, thetakeoff threshold may be related to an altitude of the aerial vehicle,velocity of the aerial vehicle, acceleration of the aerial vehicle,output to an actuator of an aerial vehicle, output measured from anactuator of an aerial vehicle, or any other characteristic of the aerialvehicle.

FIG. 2 illustrates an example of a method for controlling takeoff of anaerial vehicle, in accordance with an embodiment of the disclosure.

Initially, an aerial vehicle may be stationary on a surface 210, such asthe ground. This may be prior to starting any motors of the aerialvehicle. Any description herein of a motor of the aerial vehicle mayapply to any number of motors of the aerial vehicle, or any other typesof actuator of the aerial vehicle that may be used to drive a propulsionunit.

A command may be received to start one or more motors of the aerialvehicle 212. The command may be received from a terminal remote to theaerial vehicle. For example, a user may select an option on a remotecontroller to start a motor of the aerial vehicle. In some instances,the remote controller may be a smartphone, tablet, joystick, wearableobject (e.g., glasses, gloves, helmet, wristband), or any other type ofterminal as described in greater detail elsewhere herein. Alternatively,the command may be received from a terminal local to the aerial vehicleor built into the aerial vehicle. For example, a user may turn on apower switch or select an ‘on’ button to turn on the aerial vehicle andstart a motor. In some instances, the command may be generated by a userremote to the aerial vehicle. Alternatively, the command may be providedby a user on-board the aerial vehicle.

The aerial vehicle may determine whether it has received a command tostart a motor 214. If it has not yet received a command, the vehicle mayremain stationary on the surface. If it has received a command, a flightcontroller may output an idle motor value 216. In some embodiments, anaerial vehicle motor may be in idle mode so that the motor is runningwithout causing any actuation of a propulsion unit. The motor may berunning in idle mode without any loads except engine accessories.

The integral output (I) may be set to zero 218. The integral output maybe set to zero once the flight control outputs an idle motor value 216.In some instances, the integral output may be set to zero when it hasbeen determined that a command has been received to start a motor 214.The integral output may be set to zero while the aerial vehicle is stillon the surface (e.g., prior to taking off). The integral output may beset to zero in all directions (e.g., vertical, left/right,forward/backward, heading angle). The I value may be cleared in alldirections. In some other instances, the I value may be set to a defaultvalue, such as a constant numerical value.

A flight control command may be provided 222. In some instances, theflight control may be generated by a user. The user may use a remoteterminal, such as that described elsewhere herein. The same remoteterminal may be used to provide a command to start a motor 212 andprovide flight controls 222. Alternatively, the user may control theflight via one or more controls local to the aerial vehicle orbuilt-into the aerial vehicle. The flight control commands may be usedto control position of the aerial vehicle. The flight control commandsreceived may be provided to a flight controller on-board the aircraft,which may generate one or more signals for the operation of the motor.The motor may in turn drive one or more propulsion units, such as arotor blade, of the aerial vehicle.

If the flight control command 222 is greater than a predetermined value220, output to the motor may be increased. The output to the motor maybe increased by a constant value 226. If the flight control command isless than a predetermined value, then the output to the motor may bereduced. In some instances, the output to the motor may be reduced by aconstant value 224 until the motor is running in idle mode 216. In someinstances, it may be determined whether the vertical speed of the aerialvehicle is greater than a predetermined value 220, in which case theoutput to the motor is increased, for example by a constant value 226.If the vertical speed of the aerial vehicle is less than a predeterminedvalue 220, the output to the motor may be decreased, for example at aconstant value 224, until the motor is running in idle mode 216.

While the predetermined value 220 is exceeded (e.g., for vertical speedof the aerial vehicle) and the output to the motor is being increased,the aerial vehicle may be increasing its altitude relative to thesurface. Thus the aerial vehicle may be rising from the surface. In someinstances, the aerial vehicle may be accelerating or decelerating whilerising. Alternatively, the aerial vehicle may be rising at a constantvelocity.

An output to a motor of the aerial vehicle may be determined while theaerial vehicle is rising. In some instances, the output to the motor maybe known based on command signals from a flight controller that maydictate the output to the motor. In another example, the output to themotor may be measured using one or more sensor. The output to the motormay be indicative of the output to the motor to provide a particularaltitude. For instance, in some embodiments, it may be known what outputneeds to be provided to a motor for that type of aerial vehicle to reacha particular altitude. The output to the motor may be provided as apower output to the motor. The degree, intensity, or level of the outputto the motor may be calculated or measured. In some embodiments, anaerial vehicle may have multiple motors. Output to the motor may referto output to a single motor, average output to multiple motors, or totalaggregated output to the multiple motors.

The system may detect whether the output to the motor exceeds apredefined output value. In some instances, the system may also detectthe upward acceleration of the aerial vehicle. The system may detectwhether the upward acceleration is greater than a predefinedacceleration value. In one example, the system may detect whether theoutput to the motor is greater than a first predefined output value(Output1) and whether the upward acceleration of the aerial vehicle isgreater than the predefined acceleration value (Acc1). If both theseconditions are met 232 then it may be determined that a takeoffthreshold has been met and the aircraft has taken off 234.

The system may detect whether the motor is greater than a secondpredefined output value (Output 2). If this condition is met 232 then itmay be determined that a takeoff threshold has been met and the aircrafthas taken off 234.

It may be determined whether either of the takeoff conditions has beenmet. For example, it may be determined whether at least one of theconditions have been met (1) output is greater than Output1 and upwardacceleration is greater than Acc1, or (2) output is greater thanOutput2. If at least one of (1) or (2) has been met 232 then it may bedetermined that a takeoff threshold has been met and the aircraft hastaken off 234. In some embodiments, a second predefined output valueOutput2 may have a different value than a first predefined output valueOutput 1. For example, a second predefined output value Output2 may begreater than a first predefined output value Output1. The secondcondition (2) may be provided to make sure that the aerial vehicle hastaken off, even if detection of the first condition (1) has failed. Forexample, even if detection of Output1 has failed, or Acc1 has failed,detection of Output2 may be provided to detect if the aircraft has takenoff. In some embodiments, condition (1) will typically be met beforecondition (2). Alternatively, in some instances, condition (2) may bemet prior to detection of condition (1) being met.

After it is determined that an aircraft has taken off 234, the integralcontrol I may be calculated. Thus, normal integral control may bepermitted after it is determined that an aircraft has taken off. A PIDcontrol scheme may be used. The integral control may be calculated inthe vertical direction. The integral may also be calculated for otherdirections (e.g., right/left, forwards/backwards, heading angle). Theaerial vehicle may then be operating in a normal flight state 238 whichincludes integral control.

The process may include controlling flight of an aircraft under a firstcontrol scheme prior to detecting whether a takeoff threshold is met,and controlling flight of the aircraft under a second control schemeafter detecting the takeoff threshold is met. The first control schememay use an integral control scheme where an integral output is zero (orother default value), while the second control scheme may use a normalintegral control scheme, where the integral output may be calculated.The first control scheme may be in effect up to step 226. In someinstances, a first control scheme is in effect once the command isreceived to start the motor, up to when it is determined that a takeoffthreshold is met (e.g., which may occur at steps 232, 234). The secondcontrol scheme may be in effect after 234 (e.g., from 236 onwards). Insome instances, the second control scheme is in effect once it isdetermined that the aircraft has taken off 236.

In some instances, one or more of the steps described 228, 230, 232 maybe used to determine whether a takeoff threshold is met. It may bedetermined whether a takeoff threshold is met based on an output valueto one or motors of the aerial vehicle. For instance, based on an amountof power output to one or more motors, whether a takeoff threshold ismet may be determined. In some instances, it may be determined whether atakeoff threshold is met based on an acceleration of the aerial vehicle.In alternate embodiments, other information about the aerial vehicle,such as velocity or positional information may be used to determinewhether a threshold has been met.

The systems and methods described herein may advantageously permit theaerial vehicle to determine whether a takeoff threshold has been metwithout requiring any signals received from a source external to theaerial vehicle. For example, the aerial vehicle need not receive anysignals from external devices, such as global positioning system (GPS)satellites, towers, other aerial vehicles, remote terminals, indetermining whether a takeoff threshold has been met. The aerialvehicles also need not receive any signals from objects (e.g., signalsthat are pinged back from ultrasonic sensors on-board the aerialvehicle, or any other type of sensor that requires a signal back). Anysensors used in the determination of whether the takeoff threshold hasbeen met may be provided on-board the aerial vehicle and use informationthat is detectable on-board the aerial vehicle. Thus, signals used todetermine whether a takeoff threshold has been met may be generated fromsensors that are self-contained within the aerial vehicle and need notinteract with an environment around the aerial vehicle.

The aerial vehicle may determine whether a takeoff threshold has beenmet based on one or more signals from an inertial measurement unit(IMU). An IMU can include one or more accelerometers, one or moregyroscopes, one or more magnetometers, or suitable combinations thereof.For example, the IMU can include up to three orthogonal accelerometersto measure linear acceleration of the movable object along up to threeaxes of translation, and up to three orthogonal gyroscopes to measurethe angular acceleration about up to three axes of rotation. The IMU canbe rigidly coupled to the aerial vehicle such that the motion of theaerial vehicle corresponds to motion of the IMU. Alternatively the IMUcan be permitted to move relative to the aerial vehicle with respect toup to six degrees of freedom. The IMU can be directly mounted onto theaerial vehicle, or coupled to a support structure mounted onto theaerial vehicle. The IMU may be provided exterior to or within a housingof the movable object. The IMU may be permanently or removably attachedto the movable object. In some embodiments, the IMU can be an element ofa payload of the aerial vehicle. The IMU can provide a signal indicativeof the motion of the aerial vehicle, such as a position, orientation,velocity, and/or acceleration of the aerial vehicle (e.g., with respectto one, two, or three axes of translation, and/or one, two, or threeaxes of rotation). For example, the IMU can sense a signalrepresentative of the acceleration of the aerial vehicle, and the signalcan be integrated once to provide velocity information, and twice toprovide location and/or orientation information. The IMU may be able todetermine the acceleration, velocity, and/or location/orientation of theaerial vehicle without interacting with any external environmentalfactors or receiving any signals from outside the aerial vehicle.

An IMU may provide a signal about acceleration of the aerial vehiclethat may be used to determine whether a takeoff threshold has been met.The signal about the acceleration of the aerial vehicle may be comparedto a threshold acceleration value Acc1. In alternative embodiments,information comparing velocity information to a velocity thresholdand/or position information to a position threshold may be used.

An aerial vehicle may also be able to determine whether a takeoffthreshold is met based on an output value to one or motors of the aerialvehicle. For instance, based on an amount of power output to one or moremotors, whether a takeoff threshold is met may be determined. In someinstances, a sensor may be provided to measure the amount of output toone or more motors. The sensor may be provided on-board the aerialvehicle and/or within an aerial vehicle housing. Alternatively, theamount of output to one or more motors may be determined based on acommand signal generated by a flight controller. The output to one ormore motors may be calculated based on a desired degree of output thatis calculated by the flight controller and used to generate the commandsignal that drives the motors. In some embodiments, a measured outputfrom the motors may be used to calculate an output to the motors or todetermine a takeoff threshold of the aerial vehicle.

In some embodiments, the output to the motors may be combined with theacceleration of the aerial vehicle or any other positional informationof the aerial vehicle to determine whether a takeoff threshold has beenmet. The takeoff threshold may be when the aerial vehicle switchesbetween control schemes. Thus, the output to a motor may be combinedwith acceleration of the aerial vehicle or considered on its own todetermine when to switch from a first control scheme to a second controlscheme.

FIG. 3 provides a high level schematic of an aerial vehicle, inaccordance with an embodiment of the disclosure. An aerial vehicle 300may be in communication with a control apparatus 310. In some instances,the control apparatus may be remote terminal, examples of which areprovided in greater detail elsewhere herein. The aerial vehicle mayinclude a flight controller 320, inertial sensor 330, motor 340, commandreceiver 350 which may include an antenna 355.

The aerial vehicle 300 may be a UAV. The aerial vehicle may beconfigured to take off and land without a human on-board. The aerialvehicle may communicate with a control apparatus 310. In someembodiments, wireless communications may be used. Any form ofcommunication, such as those described in greater detail elsewhereherein, may be used. In some embodiments, a control apparatus may send asignal to the aerial vehicle to control operation of the aerial vehicle.The control apparatus may send a signal to control flight of the aerialvehicle, such as takeoff, landing, and/or flight maneuvering. Thecontrol apparatus may send a signal that controls the position of theaerial vehicle (e.g., location (along one, two, or three axes),orientation (along one, two, or three axes)). The control apparatus maysend a flight control signal which may result in control of one or moremotors of the aerial vehicle that controls propulsion units of theaerial vehicle, and results in control of the flight position of theaerial vehicle. The control apparatus may send a signal to control otheraspects of operation of the aerial vehicle. For example, the controlapparatus may send a signal that controls positioning of a payload on anaerial vehicle, or operation of the payload. The control apparatus mayalso send signals that control the type of information sensed by theaerial vehicle. The control apparatus may optionally send a signal thatinstructs the aerial vehicle to turn on (e.g., power up) or turn off(e.g., power down).

The control apparatus 310 may have an antenna that may communicate withan antenna 355 of a command receiver 350 on the aerial vehicle 300. Anyform of transceivers may be used between the control apparatus and theaerial vehicle. For example, the control apparatus may include atransceiver that may be capable of communicating with a transceiver ofthe aerial vehicle. The transceivers may permit wireless communicationsbetween the aerial vehicle and the control apparatus. In some instances,the communications may include radiofrequency (RF) communications,infrared (IR) communications, WiFi communications, or 3G/4G or othertypes of telecommunications. The communications may be two-waycommunications between the control apparatus and the aerial vehicle. Forinstance, the control apparatus may provide a signal that is sent to theaerial vehicle and controls operation of the aerial vehicle. The aerialvehicle may provide information to the control apparatus, such asinformation captured by a sensor or payload of the aerial vehicle, orpositional information relating to the aerial vehicle. Alternatively,the communications may be a one-way communication from the controlapparatus to the aerial vehicle to control the aerial vehicle.

The aerial vehicle 300 may have a flight controller 320. The flightcontroller may have one or more processors and/or one or more memoryunits. The processors may be capable of performing one or more step orcalculation described herein. The processors may perform the one or moresteps in accordance with non-transitory computer readable medium, whichinclude code, logic, or instructions for performing the steps. Thememory units may include the non-transitory computer readable medium.

The flight controller 320 may receive a signal from the command receiver350. This may include a flight control signal. A user using a flightcontrol apparatus 310 may input a flight command, which may be receivedby the command receiver, which may provide a signal indicative of theflight command to the flight controller. The flight controller mayprovide instructions to one or more motors 340 (or any other type ofactuator) of the aerial vehicle. The instructions to the motors mayinclude output power to drive the motors. The instructions may begenerated based on the flight command from the command receiver. Themotors may be used to drive one or more propulsion units, such as rotorblades, of the aerial vehicle. The motors may drive the rotor blades ofthe aerial vehicle to provide lift and/or control flight of the aerialvehicle. In some instances, the power output to the motors may be usedto determine whether the aerial vehicle has reached a takeoff threshold.

The aerial vehicle may include one or more inertial sensors 330. Aninertial sensor may include an accelerometer, gyroscope, magnetometer,or other type of sensor that may be used to determine a state of theaerial vehicle. The inertial sensor need not receive signals fromoutside the aerial vehicle. The inertial sensor may generate a signal inresponse to a detected force on the aerial vehicle. The inertial sensormay provide a signal indicative of an acceleration of the aerial vehicle(e.g., in one, two, or three directions), or angular acceleration of theaerial vehicle (e.g., about one, two, or three axes of rotation). Insome instances, the acceleration of the aerial vehicle in a verticaldirection may be measured. Measurements from the inertial sensors may beused to determine acceleration (e.g., linear and/or angular) of theaerial vehicle, velocity (e.g., linear and/or angular) or the aerialvehicle, or position (e.g., location and/or orientation) of the aerialvehicle. The inertial sensors may be part of an IMU, or may be providedindividually. The inertial sensors may include a three-axisaccelerometer and/or a three-axis gyroscope. Alternatively, multiplesingle or double-axis accelerometers and/or gyroscopes may be used.

Information from the one or more inertial sensors 330 may be sent to theflight controller 320. The flight controller may provide instructions toone or more motors 340 of the aerial vehicle. The instructions may begenerated based on the signals from the inertial sensors. In someinstances, the information from the inertial sensors may be used todetermine whether the aerial vehicle has reached a takeoff threshold.For example, a vertical acceleration of the aerial vehicle measured bythe inertial sensors, may be used to determine whether the aerialvehicle has reached a takeoff threshold. The flight controller mayconsider both the flight command received through the command receiver,and a measurement from an inertial sensor in determining whether atakeoff threshold has been met.

In some instances, information may be provided by a barometer. Thebarometer may be used to measure ambient pressure around the aerialvehicle. Information from a barometer may optionally be sent to a flightcontroller. The flight controller may generate one or more signals to amotor based on input from the barometer. The information from thebarometer may or may not be used to determine whether the aerial vehiclehas reached a takeoff threshold. In some instances, a lower pressure maybe indicative of a higher altitude. The barometer may or may not need tobe calibrated to the current environmental conditions of the aerialvehicle. In some instances, a change in pressure may be used todetermine whether a takeoff threshold has been met, or as part of theinformation used to determine whether a takeoff threshold has been met.Pressure information may be used in combination or in place of output tomotor and/or acceleration of the aerial vehicle.

In one embodiment, a control apparatus 310 may provide a takeoff commandto the aerial vehicle 300. The takeoff command may include input from auser of the control apparatus that is indicative of motor speed or powerprovided to the motor 340. In one example, a user may push a joystick ina direction to correspond to increased or decreased rotational speed ofthe motor, which may correspond to how quickly the aerial vehicle mayascend or descend. The takeoff command may be received by a commandreceiver 350 of the aerial vehicle, which may provide information aboutthe takeoff command to a flight controller 320. The flight controllermay also receive information from one or more sensors of the aerialvehicle. In some instances, the one or more sensors may include inertialsensors 330. Based on the information received, the flight controllermay generate and provide a signal to drive one or more motors of theaerial vehicle.

The flight controller may generate a signal to drive motors of theaerial vehicle in accordance with a first control scheme when a takeoffthreshold has not been met, and in accordance with a second controlscheme when the takeoff threshold has been met. One or more processorsof the flight controller may be used to determine whether the takeoffthreshold has been met. The processors of the flight controller maycalculate an output to provide to the motors in accordance with thevarious control schemes. For instance, the flight controller maycalculate an output to provide to the motors in response to the commandreceiver and the inertial sensor in accordance with a first controlscheme when the takeoff threshold value has not been reached. The flightcontroller may calculate an output to provide to the motors in responseto the command receiver and the inertial sensor in accordance with asecond control scheme when the takeoff threshold value has been reached.In some embodiments, the first control scheme may not include anintegral output of zero, while the second control scheme may include acalculated integral output. The flight controller may directly outputanalog takeoff control values (optionally, without using integralcontrol or having an integral output of zero), and after successfultakeoff switch to PID control.

The flight controller may determine, with aid of one or more processors,that a takeoff threshold has been met, based on an output to be providedto the motor. If the output to the motor exceeds an output thresholdvalue, it may be determined that the takeoff threshold has been met. Theflight controller may determine that a takeoff threshold has been metbased on a signal received by an inertial sensor. For instance, if thevertical acceleration of the aerial vehicle exceeds a thresholdacceleration value, it may be determined that the takeoff threshold hasbeen met. In some instances, the flight controller may determine that atakeoff threshold has been met based on a combination of the output tothe motor and a signal from an inertial sensor. For instance, the flightcontroller may determine that a threshold has been met when at least oneof the following conditions is true: (1) the vertical acceleration ofthe aerial vehicle exceeds a threshold acceleration value and the outputto the motor exceeds a first threshold output value, or (2) the outputto the motor exceeds a second threshold output value. The flightcontroller may be able to make the determination of whether the takeoffthreshold has been met without relying on any information other than theoutput to the motor and input from the inertial sensor. The flightcontroller may be able to determine whether the takeoff threshold hasbeen met without relying on any information other than the output to themotor and acceleration (e.g., vertical acceleration) of the aerialvehicle.

The threshold acceleration value and/or threshold output values may bepredetermined. In some instances, the threshold values may differ, basedon the type of aerial vehicle. For example, a larger or heavier aerialvehicle may have a different threshold output value than a smaller orlighter aerial vehicle. In another example, different aerial vehiclesmay have different numbers of propulsion units and/or motors withdifferent characteristics. The different aerial vehicles may havedifferent threshold output values from one another. In some instances,threshold acceleration values may remain the same for different types ofaerial vehicles, or may differ. The various threshold values may bepre-assigned for different models or types of aerial vehicles. Suchthreshold values may be pre-programmed on-board the flight controller ofthe aerial vehicle. Alternatively, the flight controller of the aerialvehicle may access the threshold values from off-board the aerialvehicle. In some instances, the threshold values may be updated. Thethreshold values may be updated by being sent to the flight controllerand being replaced on-board the aerial vehicle. Alternatively, thethreshold values may be updated off-board the aerial vehicle and themost recent threshold values may be accessed by the aerial vehicle atthe time of use. In some instances, various threshold values for varioustypes of aerial vehicles may be stored in a look-up table or otherformat. Information about the aerial vehicle type may be used to accessthe desired threshold values for determining whether a takeoff thresholdhas been met.

In some instances, an aerial vehicle may have a single motor driving oneor more propulsion units. The flight controller may determine the outputto the motor and/or use the output to the motor to determine whether atakeoff threshold has been met. In alternate embodiments, multiplemotors may be provided, each driving a single propulsion unit ormultiple propulsion units. The flight controller may determine output tothe multiple motors and/or use the output to the multiple motors todetermine whether a takeoff threshold has been met. The flightcontroller may use the acceleration of the aerial vehicle to determinewhether the takeoff threshold has been met.

The flight controller may be able to determine whether the takeoffthreshold has been met without requiring any information or signal froma source external to the aerial vehicle. For example, the flightcontroller may be able to determine whether the takeoff threshold hasbeen met without relying on a GPS signal. The flight controller may alsobe able to determine whether a takeoff threshold has been met withoutrelying on sensors that require feedback from outside the aerial vehicle(e.g., ultrasonic sensors, ultrawideband (UWB) or other sensors thatreceive echo waves from outside the vehicle).

Being able to determine whether a takeoff threshold has been met withoutrequiring any external signals may be advantageously permit the aerialvehicle to operate independently of many environmental factors. Forexample, not requiring a GPS input may permit the aerial vehicle tooperate in indoor or outdoor conditions where GPS signals may otherwisebe blocked or unreliable. In another example, not requiring feedbackfrom outside the vehicle (e.g., sensors that may require an echo todetermine altitude of the aerial vehicle), may diminish risks ofinterfering signals occurring, or having environmental factors such asmoving parts (e.g., leaves blowing in the wind) reducing the reliabilityof the echoed signal. The systems and methods described herein are alsosimple and do not require very many complicated calculations that cantake more time or processing power. The systems and methods providedherein may provide conditions that may be easily evaluated withoutperforming complex calculations that may be used in systems that look atvarious relative position and movement information compared to anoutside reference.

The systems and methods described herein may permit an aerial vehicle tooperate under a first control scheme when taking off, which will reducelikelihood of instability that may occur under traditional controlschemes during takeoff. Once it has been determined that the aerialvehicle has sufficiently taken off by meeting a takeoff threshold, theaerial vehicle may switch to a second control scheme for normal flightoperations. The aerial vehicle may determine when to switch to thesecond control scheme based on information that is provided on-board theaerial vehicle without requiring external signals. This may provide asmooth, assisted takeoff for the aerial vehicle in a wide variety ofenvironmental conditions. This may allow more novice users to easilytake off by pushing the throttle on a control apparatus. The users maynot need to perform more complicated maneuvers during takeoff, which aresuited to more experienced users, and which would be more likelyrequired if a typical PID control scheme is used.

The systems, devices, and methods described herein can be applied to awide variety of movable objects. As previously mentioned, anydescription herein of an aerial vehicle may apply to and be used for anymovable object. Any description herein of an aerial vehicle may applyspecifically to UAVs. A movable object of the present disclosure can beconfigured to move within any suitable environment, such as in air(e.g., a fixed-wing aircraft, a rotary-wing aircraft, or an aircrafthaving neither fixed wings nor rotary wings), in water (e.g., a ship ora submarine), on ground (e.g., a motor vehicle, such as a car, truck,bus, van, motorcycle, bicycle; a movable structure or frame such as astick, fishing pole; or a train), under the ground (e.g., a subway), inspace (e.g., a spaceplane, a satellite, or a probe), or any combinationof these environments. The movable object can be a vehicle, such as avehicle described elsewhere herein. In some embodiments, the movableobject can be carried by a living subject, or take off from a livingsubject, such as a human or an animal. Suitable animals can includeavines, canines, felines, equines, bovines, ovines, porcines, delphines,rodents, or insects.

The movable object may be capable of moving freely within theenvironment with respect to six degrees of freedom (e.g., three degreesof freedom in translation and three degrees of freedom in rotation).Alternatively, the movement of the movable object can be constrainedwith respect to one or more degrees of freedom, such as by apredetermined path, track, or orientation. The movement can be actuatedby any suitable actuation mechanism, such as an engine or a motor. Theactuation mechanism of the movable object can be powered by any suitableenergy source, such as electrical energy, magnetic energy, solar energy,wind energy, gravitational energy, chemical energy, nuclear energy, orany suitable combination thereof. The movable object may beself-propelled via a propulsion system, as described elsewhere herein.The propulsion system may optionally run on an energy source, such aselectrical energy, magnetic energy, solar energy, wind energy,gravitational energy, chemical energy, nuclear energy, or any suitablecombination thereof. Alternatively, the movable object may be carried bya living being.

In some instances, the movable object can be a vehicle. Suitablevehicles may include water vehicles, aerial vehicles, space vehicles, orground vehicles. For example, aerial vehicles may be fixed-wing aircraft(e.g., airplane, gliders), rotary-wing aircraft (e.g., helicopters,rotorcraft), aircraft having both fixed wings and rotary wings, oraircraft having neither (e.g., blimps, hot air balloons). A vehicle canbe self-propelled, such as self-propelled through the air, on or inwater, in space, or on or under the ground. A self-propelled vehicle canutilize a propulsion system, such as a propulsion system including oneor more engines, motors, wheels, axles, magnets, rotors, propellers,blades, nozzles, or any suitable combination thereof. In some instances,the propulsion system can be used to enable the movable object to takeoff from a surface, land on a surface, maintain its current positionand/or orientation (e.g., hover), change orientation, and/or changeposition.

The movable object can be controlled remotely by a user or controlledlocally by an occupant within or on the movable object. In someembodiments, the movable object is an unmanned movable object, such as aUAV. An unmanned movable object, such as a UAV, may not have an occupantonboard the movable object. The movable object can be controlled by ahuman or an autonomous control system (e.g., a computer control system),or any suitable combination thereof. The movable object can be anautonomous or semi-autonomous robot, such as a robot configured with anartificial intelligence.

The movable object can have any suitable size and/or dimensions. In someembodiments, the movable object may be of a size and/or dimensions tohave a human occupant within or on the vehicle. Alternatively, themovable object may be of size and/or dimensions smaller than thatcapable of having a human occupant within or on the vehicle. The movableobject may be of a size and/or dimensions suitable for being lifted orcarried by a human. Alternatively, the movable object may be larger thana size and/or dimensions suitable for being lifted or carried by ahuman. In some instances, the movable object may have a maximumdimension (e.g., length, width, height, diameter, diagonal) of less thanor equal to about: 2 cm, 5 cm, 10 cm, 50 cm, 1 m, 2 m, 5 m, or 10 m. Themaximum dimension may be greater than or equal to about: 2 cm, 5 cm, 10cm, 50 cm, 1 m, 2 m, 5 m, or 10 m. For example, the distance betweenshafts of opposite rotors of the movable object may be less than orequal to about: 2 cm, 5 cm, 10 cm, 50 cm, 1 m, 2 m, 5 m, or 10 m.Alternatively, the distance between shafts of opposite rotors may begreater than or equal to about: 2 cm, 5 cm, 10 cm, 50 cm, 1 m, 2 m, 5 m,or 10 m.

In some embodiments, the movable object may have a volume of less than100 cm×100 cm×100 cm, less than 50 cm×50 cm×30 cm, or less than 5 cm×5cm×3 cm. The total volume of the movable object may be less than orequal to about: 1 cm³, 2 cm³, 5 cm³, 10 cm³, 20 cm³, 30 cm³, 40 cm³, 50cm³, 60 cm³, 70 cm³, 80 cm³, 90 cm³, 100 cm³, 150 cm³, 200 cm³, 300 cm³,500 cm³, 750 cm³, 1000 cm³, 5000 cm³, 10,000 cm³, 100,000 cm³, 1 m³, or10 m³.

Conversely, the total volume of the movable object may be greater thanor equal to about: 1 cm³, 2 cm³, 5 cm³, 10 cm³, 20 cm³, 30 cm³, 40 cm³,50 cm³, 60 cm³, 70 cm³, 80 cm³, 90 cm³, 100 cm³, 150 cm³, 200 cm³, 300cm³, 500 cm³, 750 cm³, 1000 cm³, 5000 cm³, 10,000 cm³, 100,000 cm³, 1m³, or 10 m³.

In some embodiments, the movable object may have a footprint (which mayrefer to the lateral cross-sectional area encompassed by the movableobject) less than or equal to about: 32,000 cm², 20,000 cm², 10,000 cm²,1,000 cm², 500 cm², 100 cm², 50 cm², 10 cm², or 5 cm². Conversely, thefootprint may be greater than or equal to about: 32,000 cm², 20,000 cm²,10,000 cm², 1,000 cm², 500 cm², 100 cm², 50 cm², 10 cm², or 5 cm².

In some instances, the movable object may weigh no more than 1000 kg.The weight of the movable object may be less than or equal to about:1000 kg, 750 kg, 500 kg, 200 kg, 150 kg, 100 kg, 80 kg, 70 kg, 60 kg, 50kg, 45 kg, 40 kg, 35 kg, 30 kg, 25 kg, 20 kg, 15 kg, 12 kg, 10 kg, 9 kg,8 kg, 7 kg, 6 kg, 5 kg, 4 kg, 3 kg, 2 kg, 1 kg, 0.5 kg, 0.1 kg, 0.05 kg,or 0.01 kg. Conversely, the weight may be greater than or equal toabout: 1000 kg, 750 kg, 500 kg, 200 kg, 150 kg, 100 kg, 80 kg, 70 kg, 60kg, 50 kg, 45 kg, 40 kg, 35 kg, 30 kg, 25 kg, 20 kg, 15 kg, 12 kg, 10kg, 9 kg, 8 kg, 7 kg, 6 kg, 5 kg, 4 kg, 3 kg, 2 kg, 1 kg, 0.5 kg, 0.1kg, 0.05 kg, or 0.01 kg.

In some embodiments, a movable object may be small relative to a loadcarried by the movable object. The load may include a payload and/or acarrier, as described in further detail elsewhere herein. In someexamples, a ratio of a movable object weight to a load weight may begreater than, less than, or equal to about 1:1. In some instances, aratio of a movable object weight to a load weight may be greater than,less than, or equal to about 1:1. Optionally, a ratio of a carrierweight to a load weight may be greater than, less than, or equal toabout 1:1. When desired, the ratio of an movable object weight to a loadweight may be less than or equal to: 1:2, 1:3, 1:4, 1:5, 1:10, or evenless. Conversely, the ratio of a movable object weight to a load weightcan also be greater than or equal to: 2:1, 3:1, 4:1, 5:1, 10:1, or evengreater.

In some embodiments, the movable object may have low energy consumption.For example, the movable object may use less than about: 5 W/h, 4 W/h, 3W/h, 2 W/h, 1 W/h, or less. In some instances, a carrier of the movableobject may have low energy consumption. For example, the carrier may useless than about: 5 W/h, 4 W/h, 3 W/h, 2 W/h, 1 W/h, or less. Optionally,a payload of the movable object may have low energy consumption, such asless than about: 5 W/h, 4 W/h, 3 W/h, 2 W/h, 1 W/h, or less.

FIG. 4 illustrates an unmanned aerial vehicle (UAV) 400, in accordancewith embodiments of the present disclosure. The UAV may be an example ofa movable object as described herein. The UAV 400 can include apropulsion system having four rotors 402, 404, 406, and 408. Any numberof rotors may be provided (e.g., one, two, three, four, five, six, ormore). The rotors, rotor assemblies, or other propulsion systems of theunmanned aerial vehicle may enable the unmanned aerial vehicle tohover/maintain position, change orientation, and/or change location. Thedistance between shafts of opposite rotors can be any suitable length410. For example, the length 410 can be less than or equal to 2 m, orless than equal to 11 m. In some embodiments, the length 410 can bewithin a range from 40 cm to 7 m, from 70 cm to 2 m, or from 11 cm to 11m. Any description herein of a UAV may apply to a movable object, suchas a movable object of a different type, and vice versa. The UAV may usean assisted takeoff system or method as described herein.

In some embodiments, the movable object can be configured to carry aload. The load can include one or more of passengers, cargo, equipment,instruments, and the like. The load can be provided within a housing.The housing may be separate from a housing of the movable object, or bepart of a housing for a movable object. Alternatively, the load can beprovided with a housing while the movable object does not have ahousing. Alternatively, portions of the load or the entire load can beprovided without a housing. The load can be rigidly fixed relative tothe movable object. Optionally, the load can be movable relative to themovable object (e.g., translatable or rotatable relative to the movableobject). The load can include a payload and/or a carrier, as describedelsewhere herein.

In some embodiments, the movement of the movable object, carrier, andpayload relative to a fixed reference frame (e.g., the surroundingenvironment) and/or to each other, can be controlled by a terminal. Theterminal can be a remote control device at a location distant from themovable object, carrier, and/or payload. The terminal can be disposed onor affixed to a support platform. Alternatively, the terminal can be ahandheld or wearable device. For example, the terminal can include asmartphone, tablet, laptop, computer, glasses, gloves, helmet,microphone, or suitable combinations thereof. The terminal can include auser interface, such as a keyboard, mouse, joystick, touchscreen, ordisplay. Any suitable user input can be used to interact with theterminal, such as manually entered commands, voice control, gesturecontrol, or position control (e.g., via a movement, location or tilt ofthe terminal).

The terminal can be used to control any suitable state of the movableobject, carrier, and/or payload. For example, the terminal can be usedto control the position and/or orientation of the movable object,carrier, and/or payload relative to a fixed reference from and/or toeach other. In some embodiments, the terminal can be used to controlindividual elements of the movable object, carrier, and/or payload, suchas the actuation assembly of the carrier, a sensor of the payload, or anemitter of the payload. The terminal can include a wirelesscommunication device adapted to communicate with one or more of themovable object, carrier, or payload.

The terminal can include a suitable display unit for viewing informationof the movable object, carrier, and/or payload. For example, theterminal can be configured to display information of the movable object,carrier, and/or payload with respect to position, translationalvelocity, translational acceleration, orientation, angular velocity,angular acceleration, or any suitable combinations thereof. In someembodiments, the terminal can display information provided by thepayload, such as data provided by a functional payload (e.g., imagesrecorded by a camera or other image capturing device).

Optionally, the same terminal may both control the movable object,carrier, and/or payload, or a state of the movable object, carrierand/or payload, as well as receive and/or display information from themovable object, carrier and/or payload. For example, a terminal maycontrol the positioning of the payload relative to an environment, whiledisplaying image data captured by the payload, or information about theposition of the payload. Alternatively, different terminals may be usedfor different functions. For example, a first terminal may controlmovement or a state of the movable object, carrier, and/or payload whilea second terminal may receive and/or display information from themovable object, carrier, and/or payload. For example, a first terminalmay be used to control the positioning of the payload relative to anenvironment while a second terminal displays image data captured by thepayload. Various communication modes may be utilized between a movableobject and an integrated terminal that both controls the movable objectand receives data, or between the movable object and multiple terminalsthat both control the movable object and receives data. For example, atleast two different communication modes may be formed between themovable object and the terminal that both controls the movable objectand receives data from the movable object.

FIG. 5 illustrates a movable object 500 including a carrier 502 and apayload 504, in accordance with embodiments. Although the movable object500 is depicted as an aircraft, this depiction is not intended to belimiting, and any suitable type of movable object can be used, aspreviously described herein. One of skill in the art would appreciatethat any of the embodiments described herein in the context of aircraftsystems can be applied to any suitable movable object (e.g., an UAV). Insome instances, the payload 504 may be provided on the movable object500 without requiring the carrier 502. The movable object 500 mayinclude propulsion mechanisms 506, a sensing system 508, and acommunication system 510.

The propulsion mechanisms 506 can include one or more of rotors,propellers, blades, engines, motors, wheels, axles, magnets, or nozzles,as previously described. The movable object may have one or more, two ormore, three or more, or four or more propulsion mechanisms. Thepropulsion mechanisms may all be of the same type. Alternatively, one ormore propulsion mechanisms can be different types of propulsionmechanisms. The propulsion mechanisms 506 can be mounted on the movableobject 500 using any suitable means, such as a support element (e.g., adrive shaft) as described elsewhere herein. The propulsion mechanisms506 can be mounted on any suitable portion of the movable object 500,such on the top, bottom, front, back, sides, or suitable combinationsthereof.

In some embodiments, the propulsion mechanisms 506 can enable themovable object 500 to take off vertically from a surface or landvertically on a surface without requiring any horizontal movement of themovable object 500 (e.g., without traveling down a runway). Optionally,the propulsion mechanisms 506 can be operable to permit the movableobject 500 to hover in the air at a specified position and/ororientation. One or more of the propulsion mechanisms 500 may becontrolled independently of the other propulsion mechanisms.Alternatively, the propulsion mechanisms 500 can be configured to becontrolled simultaneously. For example, the movable object 500 can havemultiple horizontally oriented rotors that can provide lift and/orthrust to the movable object. The multiple horizontally oriented rotorscan be actuated to provide vertical takeoff, vertical landing, andhovering capabilities to the movable object 500. In some embodiments,one or more of the horizontally oriented rotors may spin in a clockwisedirection, while one or more of the horizontally rotors may spin in acounterclockwise direction. For example, the number of clockwise rotorsmay be equal to the number of counterclockwise rotors. The rotation rateof each of the horizontally oriented rotors can be varied independentlyin order to control the lift and/or thrust produced by each rotor, andthereby adjust the spatial disposition, velocity, and/or acceleration ofthe movable object 500 (e.g., with respect to up to three degrees oftranslation and up to three degrees of rotation).

The sensing system 508 can include one or more sensors that may sensethe spatial disposition, velocity, and/or acceleration of the movableobject 500 (e.g., with respect to up to three degrees of translation andup to three degrees of rotation). The one or more sensors can includeglobal positioning system (GPS) sensors, motion sensors, inertialsensors, proximity sensors, or image sensors. The sensing data providedby the sensing system 508 can be used to control the spatialdisposition, velocity, and/or orientation of the movable object 500(e.g., using a suitable processing unit and/or control module, asdescribed below). Alternatively, the sensing system 508 can be used toprovide data regarding the environment surrounding the movable object,such as weather conditions, proximity to potential obstacles, locationof geographical features, location of manmade structures, and the like.

The communication system 510 enables communication with terminal 512having a communication system 514 via wireless signals 516. Thecommunication systems 510, 514 may include any number of transmitters,receivers, and/or transceivers suitable for wireless communication. Thecommunication may be one-way communication, such that data can betransmitted in only one direction. For example, one-way communicationmay involve only the movable object 500 transmitting data to theterminal 512, or vice-versa. The data may be transmitted from one ormore transmitters of the communication system 510 to one or morereceivers of the communication system 512, or vice-versa. Alternatively,the communication may be two-way communication, such that data can betransmitted in both directions between the movable object 500 and theterminal 512. The two-way communication can involve transmitting datafrom one or more transmitters of the communication system 510 to one ormore receivers of the communication system 514, and vice-versa.

In some embodiments, the terminal 512 can provide control data to one ormore of the movable object 500, carrier 502, and payload 504 and receiveinformation from one or more of the movable object 500, carrier 502, andpayload 504 (e.g., position and/or motion information of the movableobject, carrier or payload; data sensed by the payload such as imagedata captured by a payload camera). In some instances, control data fromthe terminal may include instructions for relative positions, movements,actuations, or controls of the movable object, carrier and/or payload.For example, the control data may result in a modification of thelocation and/or orientation of the movable object (e.g., via control ofthe propulsion mechanisms 506), or a movement of the payload withrespect to the movable object (e.g., via control of the carrier 502).The control data from the terminal may result in control of the payload,such as control of the operation of a camera or other image capturingdevice (e.g., taking still or moving pictures, zooming in or out,turning on or off, switching imaging modes, change image resolution,changing focus, changing depth of field, changing exposure time,changing viewing angle or field of view). In some instances, thecommunications from the movable object, carrier and/or payload mayinclude information from one or more sensors (e.g., of the sensingsystem 508 or of the payload 504). The communications may include sensedinformation from one or more different types of sensors (e.g., GPSsensors, motion sensors, inertial sensor, proximity sensors, or imagesensors). Such information may pertain to the position (e.g., location,orientation), movement, or acceleration of the movable object, carrierand/or payload. Such information from a payload may include datacaptured by the payload or a sensed state of the payload. The controldata provided transmitted by the terminal 512 can be configured tocontrol a state of one or more of the movable object 1200, carrier 1202,or payload 504. Alternatively or in combination, the carrier 502 andpayload 504 can also each include a communication module configured tocommunicate with terminal 512, such that the terminal can communicatewith and control each of the movable object 500, carrier 502, andpayload 504 independently.

In some embodiments, the movable object 500 can be configured tocommunicate with another remote device in addition to the terminal 512,or instead of the terminal 512. The terminal 512 may also be configuredto communicate with another remote device as well as the movable object500. For example, the movable object 500 and/or terminal 512 maycommunicate with another movable object, or a carrier or payload ofanother movable object.

When desired, the remote device may be a second terminal or othercomputing device (e.g., computer, laptop, tablet, smartphone, or othermobile device). The remote device can be configured to transmit data tothe movable object 500, receive data from the movable object 500,transmit data to the terminal 512, and/or receive data from the terminal512. Optionally, the remote device can be connected to the Internet orother telecommunications network, such that data received from themovable object 500 and/or terminal 512 can be uploaded to a website orserver.

FIG. 6 is a schematic illustration by way of block diagram of a system600 for controlling a movable object, in accordance with embodiments.The system 600 can be used in combination with any suitable embodimentof the systems, devices, and methods disclosed herein. The system 600can include a sensing module 602, processing unit 604, non-transitorycomputer readable medium 606, control module 608, and communicationmodule 610.

The sensing module 602 can utilize different types of sensors thatcollect information relating to the movable objects in different ways.Different types of sensors may sense different types of signals orsignals from different sources. For example, the sensors can includeinertial sensors, GPS sensors, proximity sensors (e.g., lidar), orvision/image sensors (e.g., a camera). The sensing module 602 can beoperatively coupled to a processing unit 604 having a plurality ofprocessors. In some embodiments, the sensing module can be operativelycoupled to a transmission module 612 (e.g., a Wi-Fi image transmissionmodule) configured to directly transmit sensing data to a suitableexternal device or system. For example, the transmission module 612 canbe used to transmit images captured by a camera of the sensing module602 to a remote terminal.

The processing unit 604 can have one or more processors, such as aprogrammable processor (e.g., a central processing unit (CPU)). Theprocessing unit 604 can be operatively coupled to a non-transitorycomputer readable medium 606. The non-transitory computer readablemedium 606 can store logic, code, and/or program instructions executableby the processing unit 604 for performing one or more steps. Thenon-transitory computer readable medium can include one or more memoryunits (e.g., removable media or external storage such as an SD card orrandom access memory (RAM)). In some embodiments, data from the sensingmodule 602 can be directly conveyed to and stored within the memoryunits of the non-transitory computer readable medium 606. The memoryunits of the non-transitory computer readable medium 606 can storelogic, code and/or program instructions executable by the processingunit 604 to perform any suitable embodiment of the methods describedherein. For example, the processing unit 604 can be configured toexecute instructions causing one or more processors of the processingunit 604 to analyze sensing data produced by the sensing module. Thememory units can store sensing data from the sensing module to beprocessed by the processing unit 604. In some embodiments, the memoryunits of the non-transitory computer readable medium 606 can be used tostore the processing results produced by the processing unit 604.

In some embodiments, the processing unit 604 can be operatively coupledto a control module 608 configured to control a state of the movableobject. For example, the control module 608 can be configured to controlthe propulsion mechanisms of the movable object to adjust the spatialdisposition, velocity, and/or acceleration of the movable object withrespect to six degrees of freedom. Alternatively or in combination, thecontrol module 608 can control one or more of a state of a carrier,payload, or sensing module.

The processing unit 604 can be operatively coupled to a communicationmodule 610 configured to transmit and/or receive data from one or moreexternal devices (e.g., a terminal, display device, or other remotecontroller). Any suitable means of communication can be used, such aswired communication or wireless communication. For example, thecommunication module 610 can utilize one or more of local area networks(LAN), wide area networks (WAN), infrared, radio, WiFi, point-to-point(P2P) networks, telecommunication networks, cloud communication, and thelike. Optionally, relay stations, such as towers, satellites, or mobilestations, can be used. Wireless communications can be proximitydependent or proximity independent. In some embodiments, line-of-sightmay or may not be required for communications. The communication module610 can transmit and/or receive one or more of sensing data from thesensing module 602, processing results produced by the processing unit604, predetermined control data, user commands from a terminal or remotecontroller, and the like.

The components of the system 600 can be arranged in any suitableconfiguration. For example, one or more of the components of the system600 can be located on the movable object, carrier, payload, terminal,sensing system, or an additional external device in communication withone or more of the above. Additionally, although FIG. 6 depicts a singleprocessing unit 604 and a single non-transitory computer readable medium606, one of skill in the art would appreciate that this is not intendedto be limiting, and that the system 600 can include a plurality ofprocessing units and/or non-transitory computer readable media. In someembodiments, one or more of the plurality of processing units and/ornon-transitory computer readable media can be situated at differentlocations, such as on the movable object, carrier, payload, terminal,sensing module, additional external device in communication with one ormore of the above, or suitable combinations thereof, such that anysuitable aspect of the processing and/or memory functions performed bythe system 600 can occur at one or more of the aforementioned locations.

While some embodiments of the present disclosure have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the disclosure. It should beunderstood that various alternatives to the embodiments of thedisclosure described herein may be employed in practicing thedisclosure. It is intended that the following claims define the scope ofthe invention and that methods and structures within the scope of theseclaims and their equivalents be covered thereby.

What is claimed is:
 1. A method of assisted takeoff of a movable objectcomprising: increasing output to an actuator that drives a propulsionunit of the movable object under a first feedback control scheme;determining, with aid of a processor, whether the movable object has meta takeoff threshold; and controlling the output to the actuator using asecond feedback control scheme different from the first feedback controlscheme in response to the movable object having met the takeoffthreshold.
 2. The method of claim 1, wherein the movable object is anaircraft capable of vertically taking off and/or landing.
 3. The methodof claim 1, wherein determining whether the movable object has met thetakeoff threshold is based on at least one of the output to theactuator, the output measured from the actuator, a velocity of themovable object, or an acceleration of the movable object.
 4. The methodof claim 1, wherein determining whether the aerial vehicle has met thetakeoff threshold is performed without using signals from a sourceexternal to the aerial vehicle or using signals reflected to the aerialvehicle.
 5. The method of claim 1, further comprising: receiving acommand from a remote terminal to increase the altitude of the movableobject.
 6. The method of claim 1, wherein the first feedback controlscheme has an integral value of zero.
 7. The method of claim 6, whereinthe first feedback control scheme is configured to result in aproportional-derivative control for a vertical or a lateral direction ofthe movable object.
 8. The method of claim 1, wherein the secondfeedback control scheme has an integral value that is not zero.
 9. Themethod of claim 8, wherein the second feedback control scheme isconfigured to result in a proportional-integral-derivative control for avertical or a lateral direction of the movable object.
 10. A method ofassisted takeoff of a movable object comprising: controlling the movableobject using a first feedback control scheme; determining, with aid of aprocessor, whether the movable object has met a takeoff threshold basedon at least one of a velocity of the movable object or an accelerationof the movable object; and controlling the movable object using a secondfeedback control scheme different from the first feedback control schemein response to the movable object having met the takeoff threshold. 11.The method of claim 10, wherein the movable object is determined to havemet the takeoff threshold in response to the acceleration of the movableobject in a vertical direction exceeding a predetermined accelerationvalue.
 12. The method of claim 10 wherein the movable object isdetermined to have met the takeoff threshold in response to theacceleration of the movable object in a vertical direction exceeding apredetermined acceleration value and an output to an actuator of themovable object being greater than a predetermined output value.
 13. Themethod of claim 12, wherein the output to the actuator is determinedbased on command signals from a flight controller or measured using oneor more sensors.
 14. The method of claim 10, wherein the movable objectis an unmanned aerial vehicle including a plurality of rotors configuredto generate lift for the unmanned aerial vehicle.
 15. A system forassisted takeoff of a movable object comprising: an actuator of themovable object, an output to the actuator driving a propulsion unit ofthe movable object; and one or more processors, individually orcollectively configured to: determine whether the movable object has meta takeoff threshold, and generate a signal used to control the output tothe actuator using: a first feedback control scheme in response to themovable object having not met the takeoff threshold, and using a secondfeedback control scheme different from the first feedback control schemein response to the movable object having met the takeoff threshold. 16.The system of claim 15, wherein the movable object is an unmanned aerialvehicle comprising a plurality of rotors configured to generate lift forthe unmanned aerial vehicle.
 17. The system of claim 15, wherein the oneor more processors are configured to determine whether the movableobject has met the takeoff threshold based on at least one of the outputto the actuator, the output measured from the actuator, a velocity ofthe movable object, or an acceleration of the movable object.
 18. Thesystem of claim 15, wherein the one or more processors are furtherconfigured to determine whether the aerial vehicle has met the takeoffthreshold without using signals from a source external to the aerialvehicle or using signals reflected to the aerial vehicle.
 19. The systemof claim 15, wherein the first feedback control scheme is configured toresult in a proportional-derivative control for a vertical or a lateraldirection of the movable object and the second feedback control schemeis configured to result in a proportional-integral-derivative controlfor the vertical or lateral direction of the movable object.
 20. Thesystem of claim 15, wherein the one or more processors are furtherconfigured to determine whether the movable object has met the takeoffthreshold based on the output to the actuator or the output measuredfrom the actuator.